Aphid

[Becky]

A small bug which feeds by sucking sap from plants; a blackfly or greenfly. Aphids reproduce rapidly, sometimes producing live young without mating, and large numbers can cause extensive damage to plants.

[Britney]

Small insects that can infest [ornamental] plant leaves, and their excretions can [blacken] the leaves and interfere with [photosynthesis] and degrade the health of the plant.